Recently, my car developed a misfire. I was experiencing a recurring P0302 trouble code, indicating the misfire was in cylinder 2. Knowing there could be multiple causes of the misfire, I approached the problem by investigating the simpler possibilities first. Starting with spark plugs. After combing through the entire ignition and fuel injection systems to no avail, I decided to run a compression test, which definitively told me that the problem was in the cylinder head itself. As the car wasn’t overheating and I was seeing no signs of oil and coolant mixing, I was left with the theory that the problem was most likely a burned exhaust valve or a worn valve guide in that cylinder. At any rate, the cylinder head needed to come off to repair it.
I mulled over the possibility of rebuilding the cylinder head myself, installing new valves, guides and other parts as necessary. But, as I needed to drive the car, I decided that the most efficient way to tackle the job would be to purchase an already-rebuilt cylinder head. I waited until I had the new cylinder head in hand before I started disassembling my car.
Of course, the cylinder head wasn’t the only thing I needed. In addition to that, I needed new intake and exhaust manifold gaskets (as the intake and exhaust had to come off the engine), new exhaust studs, a new valve cover gasket, fresh coolant, and, most of all, a new head gasket. Working with a good shop manual, I tore into the job on a Saturday. In order to get the cylinder head off, I needed to remove the intake manifold, the exhaust manifold, the alternator, power steering pump, the timing belt, and camshaft pulley.
Once everything was out of the way, I removed the cylinder head bolts and lifted the head out with the engine in place. Installation was a bit more complex than you might have expected. The head bolts needed to be replaced, and needed a light coating of oil. The new head gasket was installed dry, as per factory specifications. Once the head was in place, there was a very specific torque sequence to follow in order to properly seat the new head gasket and get it to seal against the block.
After the new head was installed, the rest of it was nothing more than putting the engine back the way I found it. The timing belt had to be reinstalled. As the timing belt was recent, I saw no reason to install a new one. From there, the exhaust had to be bolted up to the engine and the intake manifold needed to be reinstalled, paying particular attention to all the electrical and vacuum connections.
As soon as everything was in place, I was able to start the engine and bleed the air out of the cooling system. The best part about it? The engine now runs properly and without the misfire.